Process for transferring markings



pressions by Patented '"Nov. 1, 1938 UNITED -.'STATES PA NT OFFICE rnocnss Fon Herbert L. Wampne'r,

to Commerc 'rasssmnmo mamas Ten-e mu, Ind allignor lal Solvents Haute, I nd., avcorporation Corporation, Torre of Maryland s Drawing. Application July 19, m5,

- Serial No. 32,234

3 Claims. (01. 41-33.)

block to correspond to the transferred sketch 7 and subsequently printing from the out block.

In the case of color printing, a separate block must be cut for each color, which means that the original sketch must be transferred successively to each .block in order to secure perfect register.

, factory,

1 hard rounded instrument.- Such a procedure is fairly satisfactoryfor transfer to a single'block." the procedure is disv terial which may be sions by pressure The problem of transferring a sketch to a series ofblocks has not been successfully solved in the past. Various coating materials, such as lithograph varnishes, have been applied to rubber blocks for receiving impressions by pressure transfer, but these materials have been unsatise particularly from the standpoint of the critical time limit within which the transfer must be made. The standard practice in the art has, therefore, avoided the used any such coating.

Rubber blocks having a pronounced gray sulfur bloom are utilized for the purpose, and the pencil sketch is transferred directly to the gray surface by rubbing the back of; the pencil lines with a Even inthis case. however, advantageous from the standpoint that errors cannot be corrected, since the removal of the sulfur bloom from the surface of the block makes the block useless for further transfers. This procedure is also quiteunsatisfactory for color printing. in. which case numerous transfers must be made. from a single sketch. A single transfer directly to the rubber block requires excessively hard rubbing and tends to stretch the fpaper on which the original sketch is made. ,Thus, after a series of transfers the original sketch is distorted and perfect register of the colored prints is unobtainable. 4

.I have now discovered an improved coating maapplied to the surfaceof rubber blocks and the like for receiving imprestransfer, and which avoids all of these prior diillculties. This material com prises essentially a cellulose ester lacquer contalning an unusually high percentage of plasti cizer. The amount of plasticizer to be employed should be sufllcient to maintain a dry film of the lacquer (1. e., a film free from volatilesolventsl m a. pressure-imprintable state but insum cient to maintain such a min in a tacky state.

For this purpose I have found that an amount of raw castor oil equal to about three times the weight of the cellulose ester imparts satisfactory Properties to a nitrocellulose lacquer. Equivalent amounts of other plasticizers may be used,

and in general it may be said that from 150-to,

450% of a non-solvent plasticizer such as raw castor oil, or from'75 to 125% of a solvent plasticizer such as .dibutyl' phsthalate, dibutyl tartrate, tricresyl phosphate, and the like, based on the weight of the cellulose ester, may be satisfactorily employed.

I have found'that in the case of transfer lacquers for application to rubber blocks a solvent mixture should be employed which is free from I hydrocarbons in order to prevent .undue softening or swelling of the rubber. Transfer lacquers for this purpose should, therefore, be formulated with a solvent mixture of esters, ketones, alcohols, and the like which are chemically inactive to rubber. The usual solvent mixtures for the cellulose ester employed ,may be used, merely omitting the common hydrocarbon diluents.

My invention may perhaps best be illustrated by the following specific examples:

Example I I Grams r 100 ml.

Bond of s lfimnts Nitrocellulose (film scrap 5' Ti 10 Raw caster oil.-' 15 Volatiles Percent by volume Ethyl acetate 2o Ethyl alcohol 66 Butyl acetate; 15

Example If Grams per 100 ml. 89nd of solvents Nitrocellulose (M sooond); .e 16 T100 Z) Dibutyl phthala te a) Volatiles Percent by volume Ethyl ML"; -2. 2o Ethyl alcohol Butyl acetate 15 The above lacquers may be thinned,-prior to .application, to the desired consistency for brushing or spraying. In general, a dilution of about 1: 1 with a. thinner of the same composition as the volatiles of the lacquer will be found to be satisfactory. After application and dryingin the usual manner, the resulting films will be found to be highly satisfactory for the reception of impressions by pressure transfer from pencil or ink markings. The solvent free films (i. e., air dry films free from volatile solvents) will be found to be non-tacky but permanently receptive to pressure imprint. The term non-tacky in this connection has the usual meaning signifying the state in which a finger may be drawn lightly over the surface without feeling sticky. This state is often referred to also as "dust free (Gardner, Physical and Chemical Examination of Paints, Varnishes, Lacquers and Colors, Washington, D. 0., 1930, page 296). The term pressure-imprintable as used herein also has the common meaning signifying the state in which full pres- .sure of a finger leaves a permanent mark upon the film.

It will be seen that blocks coated with a material of these characteristics will have many advantages over materials previously available. The coatings are sufllclently resistant so that the blocks may be handled with reasonable care and stored in the usual manner without adversely affecting the treated surfaces. also the coatings retain their pressure-imprintable character for a sufilcient length of time for ordinary commercial usage including ordinary storage periods. This characteristic may, in fact, be termed practically permanent.

The coatings, which may be pigmented in acontrasting color from that of the sketch to-be transferred yield sharp impressions with sufficlently light pressure so as not to stretch the paper and distort subsequent impressions. Any

, of the common materials may be employed for making the original sketch or tracing, such as ordinary pencil, indelible pencil, transfer inks,

and the like. An ordinary soft lead pencil will produce satisfactorily as many as six"or eight transfers. An indelible pencil will give twelve or more sharp impressions. It is, therefore, seen that a coating material of this type is 8111? satisfactory for use in preparing a series of blocks for color printing. A further advantage lies in the fact that errors can readily be corrected by removing the lacquer with solvents and applying a new coating to the block... Other advantages of materials of this type will be evident from the preceding'description.

It will be understood, of course, that my invention is not to be limited to the'particular examples disclosed above. Narious equivalent materials may be employed, and the nature of the lacquer may be modified by the addition of resins or other common ingredients of cellulose ester lacquers. A clear lacquer may be employed if the color of the base to which it is applied is satisfactory, or various pigments or dyes may be incorporated according to the nature of the transfer that is to be made. It will be evident that.

while my coating materials are especially adapted for application to rubber blocks, they may be satisfactorily employed for coating other objects for transfer use. Uses in wood block printing, linoleum printing, and the like, will readily suggest K themselves to those skilled in the art. In such uses hydrocarbons could be included in the solvent mixture, and in any. case a solvent mixture may easily be formulated to-have minimum attack on the particular base employed. In general, it may be said that any modifications or equivalents which would naturally occur to one skilled in the art may be employed without departing fromthe scope of my invention. I a

My invention now'having been described what I 1. A process for transferring markings from a sheet of paper, or similar thin material, to a solid surface which comprises applying to said solid surface a coating of a cellulose ester lacquer containing sufllcient plasticizer to maintain a solvent free film of said lacquer in a pressure imprintable state, but insuillcient to maintain such a'film in a tacky state, drying said coating to a solvent'free condition and transferring the markings from the said thin material to the resulting lacquer film solely by pressure transfer.

2. A process for transferring markings from a sheet of paper, or similar thin material, to a solid surface which comprises applying to said solid surface a coating of a cellulose ester lacquer containing from 150 to 450% of a non-solvent'plasti- I cizer based on the weight of the cellulose ester,-

- drying said coating to a solvent free condition and transferring the markings from the said thin material to the resulting lacquer film solely by pressure transfer. a

, 3.- A process for transferring markings" from a sheet of paper, or similar thin material, to,a solid surface which comprises applying to said'solid surface a coating of a cellulose ester lacquer contaming from '75 toof a solvent plasticizer based on the'weight of the cellulose ester, drying said coating to a solvent free condition and transferring the markings from the 'said thin material to the resulting lacquer film solely by pressure transfer.

HERBERT 1.. wamm es 

